The June 12, 2017 M6.3 Karaburun-Lesvos earthquake of the Northern Aegean Sea: Aftershock forecasting and stress transfer

• Published in: Tectonophysics 2021-09, Vol.814, p.228945, Article 228945
• Main Authors: Utkucu, Murat, Nalbant, Süleyman S., Pınar, Ali, McCloskey, John, Nicbhloscaidh, Mairead, Turhan, Fatih, Yalçın, Hilal, Kızılbuğa, Serap, Coşkun, Zeynep, Kalkan Ertan, Esra, Gülen, Levent
• Format: Article
• Language: English
• Subjects: 2017 Karaburun-Lesvos earthquake; aftershock forecasting and triggering; Aftershock monitoring; Aftershocks; Azimuth; Broadband; Data acquisition; Deployment; Earthquake prediction; Earthquakes; Fault zones; Faults; Finite source model; Forecasting; Monitoring; Real time; Seismic activity; Sequencing; Stations; Stress; Stress transfer; Tectonics; Tensor analysis; Tensors; Waveforms
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/j.tecto.2021.228945

The June 12, 2017 Karaburun-Lesvos (North Aegean Sea) earthquake occurred along the NW-SE trending Lesvos fault, along the southern strand of the North Anatolian Fault Zone. In the present study seismotectonic aspects of the 2017 Karaburun-Lesvos earthquake and its aftershock sequence are studied. A rupture model based on finite source analysis of the teleseismic waveforms has shown that the earthquake was associated with a failure of single asperity. About 5 days after the mainshock a temporary seismic network of 8 broadband stations (Real-time Aftershock Forecasting in Turkey, RAFT) had been deployed along the Turkish Aegean coast to enhance the existing regional seismic monitoring and the acquired data have been used to relocate the aftershocks. The temporary deployment significantly improved the aftershock detection capacity and resulted in more precise locations. Prior to the monitoring enhancement a single widespread aftershock cluster was observed; however, the relocated aftershocks, augmented by the RAFT stations, identified two distinct spatially isolated clusters. The first day of the aftershock sequence has been used for retrospective real-time aftershock forecasting up to 7 days following the mainshock. Our results indicate that with a method developed by Omi et al. (2013) can be used forecasting aftershocks over a week period successfully employing incompletely detected aftershocks occurred in the first day following the mainshock. Stress tensor analysis of the 33 aftershock source mechanisms has shown local dominance of the extensional tectonics with azimuth and plunge pairs for the three principal stress axes as σ1, σ2 and σ3 are (255°; 76°), (131°; 8°) and (39°; 11°), respectively. Coulomb stress changes imparted by the mainshock onto the nodal planes of the aftershocks show that ~67% of the 33 aftershocks have been exposed to positive stress change at least on one of the nodal planes. •Relocated aftershocks identified two distinct spatially isolated aftershock clusters.•Incompletely detected aftershocks can be used for operational aftershock forecasting.•~67% of the aftershocks were exposed to positive mainshock stress changes.